Use of fecal analysis to determine seasonal changes in the diet of wintering Harlequin Ducks at a herring spawning site

Harlequin Ducks (<i>Histrionicus histrionicus</i>) Scavenge Sea Urchin Fragments from Foraging Sea Otters (<i>Enhydra lutris</i>)

“…Harlequin Ducks typically forage on intertidal snails, crabs, amphipods, and limpets (Vermeer 1983;gaines and Fitzner 1987;rodway and cooke 2002;Bond and Esler 2006;Esler and Bond 2010) in waters less than 5 m deep (Holm and Burger 2002), whereas red Sea Urchins occur in the shallow subtidal area to depths up to 125 m (Mccauley and carey 1967), and are rare in Harlequin Duck diets. Urchin size can affect their quality as prey, with large reproductive urchins being higher in lipids and key nutrients than the smaller immature individuals that might be available to Harlequin Ducks unassisted by Sea Otters (Oftedal et al 2007).…”

“…During winter, Harlequin Ducks feed intensely to meet the costs associated with maintenance and thermoregulation (goudie and Ankney 1988) and to attain optimal body mass needed for successful repro duction (Bond and Esler 2006;Esler and Bond 2010). in wintering habitats, Harlequin Ducks eat small intertidal invertebrates, such as snails, crabs, amphipods, and limpets, which they obtain by head-dipping and shallow diving (Vermeer 1983;gaines and Fitzner 1987;rodway and cooke 2002;Bond and Esler 2006;Esler and Bond 2010).…”

More on the validation of fecal samples for the large-scale study of dietary differences between two sympatric carnivores

“…Discrepancies between gastro-intestinal contents and various other sources were noted in fish (Randall and Myers 2001), birds (Eybert and Constant 1992, Harris and Wanless 1993, Casaux et al 1997, Derby and Lovvorn 1997, Gonzalez-Solis et al 1997, Rodway and Cooke 2002, Punta et al 2003, and mammals (Wydeven and Dahlgren 1982, McInnis et al 1983, Cavallini and Volpi 1995. These discrepancies between sample sources were attributed to the fact that stomach content analysis allows the calculation of proportions by volume (or mass) and therefore, greater resolution.…”

Behavior and Diving of Harlequin Ducks Wintering at Isle au Haut, Maine

“…Although diurnal activity budgets and diving activities in wintering Harlequin Ducks have been studied in Newfoundland (Goudie and Ankney 1986), Alaska (Fischer 1998;Fischer and Griffin 2000), and British Columbia (Goudie 1999;Torres et al . 2002), feeding behavior and foraging patterns are not necessarily the same throughout a species range because of differing habitat, prey species and availability, and environmental conditions (Nilsson 1970;Paulus 1988;Mittelhauser 2000;Rodway and Cooke 2002). From 125 to 250 Harlequin Ducks wintered at Isle au Haut, Maine in the 1990s (Mittelhauser 2000;Mittelhauser et al .…”